All known types of airships, including rigid airships, keel or semi-rigid airships or pressurized non-rigid airships, possess one or more landing wheels which are arranged on the gondola and sometimes on the lower tail fin. After landing on these wheels, the airship is held through bow lines by a ground crew until a mobile or stationary mooring mast or pylon is coupled with the airship.
The coupling location between the airship and the mooring mast is either located at the bow of the airship or, for a low mast, under the belly of the airship in front of the center of lift.
Masts for anchoring at the bow of the ship must be able to withstand a high tilting moment. Such masts are highly loaded and very heavy in order to achieve the required stability for a mobile mast. Stationary masts are anchored into the ground and require high anchoring forces.
Masts for anchoring at the forward body section of the airship, the tilting moment is considerably smaller, typically 50%, but instead a rolling moment arises in the airship because the ship is restrained below the aerodynamic center of wind pressure, that is to say when a wind blows laterally against the airship, the airship will roll sideways at a considerable roll angle, that can be than 25.degree., until it has again turned itself into the wind.
At least for pressurized non-rigid airships, this type of anchoring is critical due to the large forces acting on the envelope skin. Therefore, this type of anchoring is hardly ever practice used in.
Fundamentally, the anchoring of an airship is carried out in such a manner that the airship is held or restrained at a location forward of the aerodynamic center of wind pressure, so that when the wind blows laterally against the airship, the airship turns into the wind like a weather vane. In this manner, the airship offers the least aerodynamic resistance.
It is a disadvantage of such an anchoring that an anchor mast or mooring mast is absolutely necessary for anchoring an airship. This sharply limits the operation of airships, because it can only take off and land at a prepared base. A mooring mast must be available for every off-field landing. For this reason, ferrying trips over long distances are not possible or only possible with a large expenditure and effort for preparations. When unplanned off-field landings are necessary, for example, due to a breakdown of the airship, the result is often a total loss, as is shown by airship history. Moreover, such mooring masts are expensive.
A further disadvantage of anchoring an airship with the aid of a mast is that the mast, or for mobile masts the mast vehicle, represents an impediment or obstacle for the landing airship because the airship cannot exactly maintain the intended landing point due to shifting winds. The airship then drifts into the mast and is usually severely damaged. Examples are known for the last five years in which, of sixteen pressurized non-rigid airships operating around the world, the envelope of two of these ships became "a total loss" in such an accident.
However, the problem of over-shooting the mast is partially circumvented by using movable masts, which are only driven into position once the airship is stationary. The disadvantage of such a method is, however, to be seen in that the airship must be held by a large holding crew (approximately 15 persons are necessary for holding a small airship of approximately 6000 m.sup.3) until the mobile mast is driven into place and anchored.